Field of the Invention
The present invention relates to a generator, and more particularly, to a self-powered generator which can output power suitable for a predetermined application without a separate external power source.
Description of Related Art
The skin of a living organism of people is filled with sensors designed to perceive various external physical or chemical stimuli and transfer information on the stimuli to the brain such that homeostasis can be maintained. Various sensors that can detect changes in pressure, temperature, light, absorbed chemicals etc. should be integrated into artificial skin that covers a biomimetic robot in order to achieve an auto-feedback function equivalent or superior to that of the living organism. In order to address this requirement, there have been reports on stretchable electronic sensors and electrical wiring embedded into the artificial skin.
Typically, a certain amount of electric energy (electric power) is required to operate an electronic sensor and transfer a signal to a central processing unit (CPU) regardless of the type of the sensor to be used (passive or active). In many sensors, the energy is supplied through long and complicated electric wiring from a separate power source. In this case, however, a considerable amount of joule heat as well as the restriction of sensing areas is unavoidable. One possible solution to this power supply issue can be conceived. This involves self-powered artificial skin (SPAS) without electric wiring, to which sensors can be integrated with high density to closely mimic living skin.
Considering mechanical energy generated from the stretching and bending of the skin, it is desirable to find a method of powering the SPAS based on piezoelectric energy harvesting. Over the past decade, self-powered sensing systems based on piezoelectric nanogenerators (NGs) have been developed for a variety of sensing applications by a number of study groups. However, no NGs suitable for the SPAS that have a high mechanical stretchability, a small thickness, environmental compatibility and a large area have been developed yet.
A method of fabricating a flexible NG was disclosed (e.g. Korean Patent Application Publication No. 10-2012-36579). However, this method requires high-temperature heat treatment of a piezoelectric device layer for crystallization, as well as separate transfer of the piezoelectric device layer to a flexible substrate. This method also discloses the use of perovskite (PZT, BaTiO3). In this case, however, the crystal orientation of a material must be attained through the induction of a high electric field so that ferroelectricity can be used.
The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.